Balance and stability of an aircraft is affected by the aircraft's center of lift and center of gravity. To maintain balance and stability, the optimal position for the center of gravity is at or near the aircraft's center of lift. Thus, an aircraft is balanced when its center of lift and center of gravity align within a balance range.
Generally, the center of lift is set by the primary lifting surface, which is typically the aircraft's main wing. The position of an aircraft's center of gravity varies depending on the aircraft's weight distribution. More specifically, an aircraft's center of gravity moves forward or aft relative to the fuselage to a point where all weight is concentrated.